This invention relates to a magnetic record member for use in a magnetic recording/reproducing system such as magnetic disc or drum systems, and a process for manufacturing the same.
Generally, in a magnetic recording/reproducing system including a magnetic recording/reproducing head and a magnetic record member, the process for recording or reproducing data on the record member is performed in the manner described below. First, upon initiation of operation, the head is brought into contact with the record member and then the record member is driven to rotate at a given speed to build up an air-film space between the head and the record member while the recording or reproducing operation is performed. This process is called a "contact-start-stop process" (referred to hereinafter simply as the "CSS" process). In this process, upon the completion of operation, the rotation of the record member is stopped in the state where the head and the record member are maintained in frictional contact with each other, as is the case in the starting position.
Such frictional contact causes many scars in both the record member and the head as well as some wear in the record member. Further, when the elements are maintained in frictional contact, a slight change in the attitude of the head results in a non-uniform load being imposed on the head, so that the head and the recording medium are damaged. Moreover, during the recording or reproducing operation, large frictional forces often arise between the head and the record member, causing the breakage of these elements when the head is suddenly brought into direct contact with the record member. To protect the head and the record member against such damage, a lubricant material is often provided on the surface of the record member. As such a lubricating material, oils such as perfluoroalkyl polyether, silicon oil and fluorosilicon oil have been proposed. The use of such oils, however, involves various disadvantages, as will be described hereunder.
In general, in response to the need for enhancement of the recording density of the record member, the spacing of the head from the member tends to be reduced, in addition to the reduction in the surface roughness of both the record member and the sliding face of the head. As is well known, however, any layer of liquid such as oil or water lying between such contacting surfaces with a limited roughness provides a large adhesiveness effect therebetween. Consequently, if oil is employed as a lubricant on the record member, or if the record member is placed in a humid atmosphere causing the adsorption of moisture on the record surface, a large force attributable to such adhesiveness acts between the record member and the head to resist the rotation of the record member at the starting of operation. Consequently, the head-supporting spring breaks down and, simultaneously, the head is crushed.
Several proposals for the use of lubricant materials other than oils have been made with a view to improving the resistance of the record member against wear when in contact with the head. For example, the Japanese Patent Publication No. 24805/1978 (corresponding to U.S. application Ser. No. 360,228, filed May 14, 1973) proposes the deposition of fine particles of fluorides, such as of Ce, La, Pr, Nd, or Sm, on a magnetic record medium formed of a polymer binding agent containing magnetic particles, by electromigration. Fluoride particles thus deposited however, do not adhere well to the record surface, so that they readily peel off from the record member due to sliding contact with the head. In addition, the peeled-off particles easily adhere to portions of the head to prevent it from maintaining a stable flying height, which leads to head crushing.